Method of reenforcing bridges



y 1936- A. c LEAKE 2,042,180-

METHOD OF REBNFORCING BRIDGES Filed Oct. 20, 1933 2 Sheets-Sheet lATTORNEYS Y 1936- A. G. LEAKE METHOD OF REENFORCING BRIDGES 2Sheets-Sheet 2 Filed Oct. 20, 1933 Fay. 8

ATTORNEY5 Patented May 26, 1936 UNITED STATES Mn'rnon 0F REENFORCINGBRIDGES Arthur G. Leake, Bridgeport, Conn. Application October 20, 1933,Serial No. 694,418 7 Claims. (01. 29-151 This invention relates to newand useful improvements in methods of reenforcing or strengthening pinconnected trusses or the like.

The invention has for an object to provide a simple and comparativelyinexpensive method of reenforcing or strengthening pin connected bridgetrusses or similar structures whereby bridges or other structuresincluding such trusses may be strengthened for use for carrying muchheavier loads than those for which the bridges were originally designed.

Another object is to provide a method as stated and which may be used orpracticed to strengthen a bridge while the same is in use and withoutinterfering with the usual trafiic using the bridge.

A further object is to provide a method which does not require thebuilding of false work to carry the joints of a bridge and which doesnot involve the building of a temporary truss or temporary trusses tosupport the load while the work of reeniorcing the bridge is being done.

A still further object is to provide such a method which may be usedwhere the available space or clearance is limited.

Other objects and advantages will become apparent from a considerationof the following detailed description taken in connection with theaccompanying drawings wherein examples of the use of the method of theinvention is shown.

However, it will be understood that the invention is not limited to thedetails disclosed but includes all such variations and modifications asfall within the spirit of the invention and the scope of the appendedclaims.

In the drawings:

Fig. 1 is a side elevational view illustrating a portion of an I-barbridge to be reenforced or strengthened by the method of the presentinvention;

Fig. 2 is a sectional view on an enlarged scale illustrating the methodof anchoring or attaching reenforcing or strengthening members to a pinof the bottom chord of the bridge;

4 Fig. 3' is a similar view illustrating a slightly difierentarrangement which may be used for securing an end of a strengtheningmember or bar to an intermediate pin of the bottom chord of the bridge;

Fig. 4 is a similar view illustrating another arrangement;

Fig. 5 is a. detailed sectional view illustrating the application of apipe spacer;

Fig. 6 is a typical plan view showing the application of the reenforcingor strengthening members to a pin of the bridge and showing the spacersin place;

Fig. 7 is a view similar to Fig. 4 but illustrating a slight variation;

Fig. 8 is a sectional view on an enlarged scale and illustrating theapplication of the method as the same is used in attaching or securing adiagonal reenforcing piece to a pin of the upper chord of the bridge;

Fig. 9 is a view similar to Fig. 8 illustrating a 10 slight variation;

Fig. 10 is a-similar view illustrating a further variation particularlyas applied to the securing of the upper end portions of oppositelyinclined diagonal strengthening members to the upper 15 bridge chord;and

Fig. 11 is a view similar to Fig. 10 and showing a further slightvariation.

Referring in detail to the drawings and at first particularly to Fig. 1,the bridge there shown is 20 generally designated l5 and includes a topchord l6, a bottom chord I! and vertical struts 18. In the presentinstance I am not particularly concerned with the upper chord Hi, thepresent invention having particular relation to a method of 25"strengthening or reenforcing the lower chord l1 and the applying ofdiagonal members I9 and 2B. These diagonal members may be used tosupplement or assist diagonal I-bars already in place or they may beapplied in the absence of diagonal 3U these bridges were built in a timewhen traffic 35 was not nearly so heavy as at the present, and whilesuch bridges were not designed to sustain the loads to which they aresubjected the cost of their replacement is in many instances prohibijtive. The present invention provides a method 40 whereby these bridgesmay be strengthened and reenforced at comparatively little expense andwithout any interference with their normal use. According to the presentinvention additional load carrying members are incorporated in the lowerchord of the bridge and new or additional diagonal members are appliedto' the bridge whereby its load carrying capacity is appreciably raised.In actual practice the reenforcements herein disclosed were designed toraise the load limit of the 50 bridge from a 12 ton truck to a 30 tontruck.

To simplify the description the various pins 22 in the lower chord ofthe bridge have been designated A, B, and C. Fig. 2 illustrates themethod oi anchoring or securing the adjacent ends of strengtheningmembers or bars 23 to the pin A. According to the method as heredisclosed, a plate 24 of the desired thickness and size is provided andthrough this plate there is drilled an opening of the size or diameterof the pin A and the plate is then split as by a saw, the cut extendingthrough the drilled open ing in the plate and dividing the plate intotwo sections. This cut may be along the line 25 and after the plate iscut it is assembled on the pin accommodating the pin in the abovementioned drilled opening.

The plate is preferably located approximately in the center of the trussand since the plate is divided or split as above explained the assemblyof the plate on the pin is greatly facilitated. This is particularlytrue where the clearance is limited since the upper section of the platemay be slipped or worked into place over the pin and then the lowersection welded to it giving proper alignment about the pin. Also, itwill be apparent that the plate may be assembled on the pin withoutdisturbing the I-bars pivoted to the pin and without the necessity fordismantling any portion of the bridge. The top section or portion of theplate is applied or located and thenthe lower section or portion iswelded to it, the sections being welded together along the line on whichthey are cut as shown at 26.

To increase the bearing surface between the plate 24 and the pin A andto strengthen said plate blocks 21 are welded about their edges to theplate as at 28, one of these blocks being applied to each side of theplate. Each block is provided with an arcuate groove or recess 29 thesurface of which groove or recess conforms to and engages the surface ofthe pin A. It will be noted that these blocks 21 are arranged to spanthe cut 25 at that side of the pin to which most of the stress will beapplied. The adjacent ends of the strengthening members or bars 23 maynow be welded to the plate 24 as at 30, it being noted that these barsare applied in such position that they span the welded joint between thesections of the plate and it will be understood that the end portions ofthe bars are applied one against each side of the plate.

If desired, bars 23 need not be applied to the plate 24 until after aplate 3| has been applied to the pin B since the opposite end portionsof bars 23 are to be secured to such plate 3|. Fig. 3 illustrates themethod of applying plate 3| to the pin B and the method is substantiallythe same as that already described in connection with the application ofplate 24 to the pin A. Plate 3| is of the desired thickness and is cuttothe proper size to sustain the load which will be placed on it and anopening is then drilled in the plate, the opening being of the properdiameter to receive the pin B. Next, the plate is split or sawed asalong thelines 32 and 33, the cuts entering the above mentioned drilledopening and extending from the opposite ends of the plate whereby theplate is divided into a pair of sections. The upper section is thenassembled on the pin and the lower section welded to it along the linesof the cuts as at 34. This plate is also arranged approximately in thecenter of the truss so as to align with the plate 24.

Since the plate 3| is cut in two and then applied to the pin B it willbe apparent that the plate may be easily applied without disassemblingany parts of the bridge or other structure and that the sections of theplate may be worked into place even though there is but small clearance.After this plate is in place the other ends of the bars or strengtheningmembers 23 may be secured to it as by Welding about the edges of saidbars as 35. Attention is directed to the fact that these bars span thecut 33 and the bars are slightly spaced so that they receive the platebetween them.

After one end of a bar 23 has been welded in place the bar isprestressed to the same unit stress as the old I-bars under dead load.This prestressing is accomplished by heating the bars 23 to expand themto the desired length according to the method described in my priorPatent No. 1,770,932 issued July 22, 1930, and then while these bars 23are under stress or thus expanded, the other end is welded to the otherplate at the next joint or pin 22. Thus, it will be seen that the barsare prestressed or expanded before they are welded at the second end andwhen they cool or return to normal temperature they immediately take uptheir share of the load.

Reenforcing'or strengthening bars 36 extend between the pin B and thepin C and these bars are also slightly spaced apart so as to receiveplate 3| between a pair of their end portions and such end portions arewelded to said plate about the edges of the portions as at 31. These endportions of the bars overlap or straddle the welded cut 32 of theplatewhereby they serve to additionally strengthen the plate. If it isdesired that the plate have additional bearing surface on the pin thenblocks similar to the blocks 21 may be applied to the plate.

Figs. 4, 5 and 6 illustrate the method of applying a plate 38 to the pinC, the said plate forming an anchoring or mounting means for the ends ofthe bars 36 remote from the plate 3|. This plate 38 is of the desiredshape, size and thickness and a hole of the diameter of the pin 0 isdrilled through the plate and the plate is then sawed or otherwise cutfrom its opposite ends as at 39 and 40 each of said cuts entering thedrilled opening. This, of course, divides the plate into a pair ofsections and the upper section is worked into place on the pin C and thelower section is then welded to the upper section along the lines of cut39 and 40 as at 4|. Preferably, the plate 38 is arranged substantiallyin the center of the truss in alignment with the plates 24 and 3|.

After the plate 38 has been mounted the ends of the bars 36 adjacentsaid plate are welded to the plate as at 42. Of course, these bars areslightly spaced apart so that they receive the plate between them andprior to the welding of the bars to the plate the bars are heated andexpanded and are welded to the plate while so expanded so that on theirreturn to normal temperature they will be prestressed. As shown, thebars overlap the cut 40 and if an additional bearing surface is requiredbetween the plate and pin, blocks, similar to the blocks 21, may beapplied. Bars 43 are arranged in spaced relation so as to receive theplate 38 between them and end portions'of these bars are welded to theplate as at 44 itbeing noted that the bars overlap or span the weldedcut 39 of the plate.

Fig. 6 clearly shows the manner in which the plate 38 is arranged on thepin 0. This figure is a typical plan view and discloses the arrangementby means of which the plates 24 and 3| heretofore described and otherplates hereafter to be described are maintained in positionapproximately centrally of a truss. To accomplish this split pipespacers 45 are applied about the pin C at opposite sides of the plate38'and thev sections of the respective spacer are. then welded togetheras along the lines 46.

It will be understood that the end portions of the bars 43 remote fromthe plate 38 are anchored or secured to the next pin of the bridge orother structure and it will further be understood that such bars areprestressed as described in my above noted patent prior to the anchoringof the said other end portions. As shown in Figs. 4 and 7 the lower endportions of the added or additional diagonal members or bars l9 arewelded to the plate 38 as at 41. These bars are arranged in spacedrelation so that they receive the plate between them and the upper endportions of these bars are secured or anchored as will later bedescribed.

The strengthening or reenforcing members 29 as shown in Fig. 4 are nothere shown as ar ranged in pairs but one such diagonal being disclosedand this diagonal has its lower end arranged to bear against an edge 48of the plate 38. and said lower end is secured to the plate as by a pairof short straps 49 arranged one at. each side of the plate and welded toit as at 50. These short straps extend beyond the plate and receive thelower end of bar 29 between them and are welded to said bar as at 5|. Atits upper end the bar 2|] is secured or anchored as will later bedescribed and it will be understood that the bars l9 and 29 areprestressed according to the. method disclosed in my Patent No.1,770,932 above referred to.

Fig. 7 discloses a slight variation of the method of Fig. l and wherepossible the same reference characters have been employed. The plate ofFig. 7 is not of the same configuration as plate- 38 and is thereforegiven a new reference number being designated 52. This plate 52 isdrilled and is then cut along the lines 39 and 49 and then weldedtogether after being applied to the pin and has the end portions of thebars 35 and 43 welded to it as at 42 and M respectively. Also, diagonalbars I 9 are welded tothe plate as at 41. The essential differenceresides in the fact that diagonal bars 53 are substituted for thediagonal bar 20 of Fig. 4 and these bars 53 are slightly spaced apart soas to receive the plate between their lower portions, such lowerportions are welded to the plate as at 54. Of course, the upper ends ofthese bars 53 are suitably anchored and the bars are prestressed asabove described and as disclosed in my patent previously referred to.

Figs. 8, 9, l0 and 11 illustrate several variations of the method asapplied to the securing or anchoring of the upper ends of the diagonalsto the pins of the top chord IQ of the bridge. lEteferring first to Fig.8, the upper end portions of the diagonal bars or strengthening membersl9 are to be anchored to a pin 55 of the top chord of the bridge. Toaccomplish this, a plate 56 of the desired thickness, size and shape isprovided and at the proper point is drilled to provide a hole of thediameter of the pin 55. Next, this plate is sawed or otherwise severedas along the lines 57 and 58, the said saw cuts extending from oppositeends of the plate and each entering the drilled opening whereby theplate is divided into a pair of sections. These sections are worked inplace on the pin 55 and are then Welded along the lines of the cut as at59.

The plate is located approximately in the center of the truss and itwill be noted that owing to the structure of the top chord there is verylittle clearance. However, when the plate is cut in two it. may be.easily assembled on the pin and then welded together. This, of course,is accomplished without disconnecting or disassembling any of the bridgeTo increase the bearing surface between the plate 56' and the pin 55,blocksin-the form oi. plates 60. may be welded against each side of theplate and each block or plate is provided with an arcuate recess 6|, thecurvature of the edge of which is the same as that of the outer surfaceof the pin whereby the blocks bear against the pin.

It will be noted that the blocks 60 span the welded cut 58 of the plateand they therefore serve to strengthen the plate. After the plate is inplace the diagonal bars H! are heated to ex: pand them and then theupper ends of the bars are welded to the opposite sides of the plate asat 62 it being noted that: such bars span the welded cut 51 of the.plate. This last welding operation takes place while the bars are heatedand expanded so that they are prestressed on returning to normaltemperature and immediately take up their share oi the, load.

Fig. 9 shows av slightly different arrangement and in this figure theupper bridge chord pin is designated 63 and a plate applied to this pinis designated 64. Such plate has an opening drilled theret-hrough theopening being of the diameter of the pin and the plate is then sawed orotherwise cut through from its opposite ends as along the lines 65 and6.6, each cut entering the drilled opening. It will be noted that thelines of the cut 65 and 6.6 are arranged at an angle to one another buteach cut entering the opening, the plate is divided into two sections.With the plate divided into two sections. the upper section may behooked over or assembled on the pin and then the lower section may bewelded to the upper section along the lines of cut asat 61. Owing tothey presence of the upper flange or plate of the top chord there. isbut slight clearance and the severing of the plate 63 makes possible itsassembly on the. pin, without dismantling any of the bridge structure.

To increasethe bearing surface between the plate and pin, blocks in theform of plates 68 may be welded against opposite; sides of the plate,the weld being indicated at 69. Each of these blocks has an arcuaterecess Hi, the edge of which is. curved to embrace the pin. Preferably,these blocks are arranged in position spanning the welded cut. 56 of theplate so as. to strengthen the latter. The upper end portions of thediagonal bars or strengthening members [9 receive the plate 64 betweenthemand these upp r nd D 1- tions are welded to the plate as at H andspan the welded cut 65 of the plate to strengthen the same. After oneend portion of each of these members. l9 has been anchored, the memberis heated to expand it and while'itis so expanded its other end portionis anchored whereby when the member returns to normal temperature it isprestressed and-immediately assumes part of the load.

Referring now to Figrlfl, the pin of the top chord of the bridge isdesignated 12 and has applied to it a plate l3 said plate being somewhatL-shaped and arranged on the pin at a point approximately in the centerof the truss. An opening of the diameter of the pin 12 is drilledthrough the plate 13 substantially at the juncture of the arms of theplate and then the plate is cut to divide it into upper and lowersections. The lines-of out are indicated at M and 15 and are throughthe'plate from the outer ends of its arms and eachcut enters the drilledopening. Next, the uppersection of the plate is worked into positionover the pin and then the plate sections are welded together along thelines of the cuts as at 16.

After the plate is in position, the upper end of a diagonal bar 20 maybe'anchored to one of the arms of the plate as by means of short piecesor straps Tl welded one'to each side of the upper end portion of thebar. such straps projecting beyond the end of the bar and receiving aportion of the platebetween them. When the bar has been heated to expandit the projecting ends of the pieces 1! are welded to the plate as at18, the said pieces spanning the welded cut 15 of the plate. To theother armof the plate the upper end portion of' bars or strengtheningmembers l9 may be secured." Said upper end portions receive the otherarm of the plate between them and after being heated so that they areexpanded to the desired extent they are welded to the plate at at 19.These welded. portions of the bars [9 span the welded cuts 14.

Fig. 11 shows a slight variation of the arrangement of Fig. 10 and wherethe parts are the same the same reference characters have been employed.According to Fig; 11 after the plate 13 is in position the upper endportions of diagonal bars or strengthening members 80 are secured to therespective arms of the plate. The upper end portion of each bar 80 isshown as abutting the outer end of one arm of the L-shaped blade and ashort piece or strap 8| 'is welded to each side of the upper end portionof each of the bars 80, the weld being indicated at 82. These piecesproject beyond the ends of the bars so that each arm of the plate hasits end portion received between a pair of the pieces 8| and after thebars are expanded the said projecting end portions of the pieces arewelded to the plate at 83 this welding operation being performed whilethe bars are expanded so that when they return to normal temperaturethey are prestressed and immediately assume part of the load.

From the foregoing description taken in connection with the accompanyingdrawings it will be apparent that according to the method of the presentinvention a pin connected bridge may at comparatively little expense bestrengthened or reenforced so as to very appreciably raise its loadcarrying limit. Additional bars may readily be incorporated in thebottom bridge chord and additional diagonal bars may be added. Owing tothe prestressing of the new bars they immediately assume their propershare of the load.

Owing to the fact that the various plates are cut in two after beingdrilled the plates may be readily positioned on the bridge pins eventhough there is but small clearance. Further, this step enables theoperator to mount the plates on pins without disconnecting the I-barsalready connected with the pins. Of course, blocks similar to the blocks21 of Fig. 2 and 60 of Fig.8 may be added to the other plates when it isdesired to provide additional bearing surface between the plates andpins. The spacers 45 are used in each instance to maintain the platesproperly located approximately centrally of the trusses and it will beapparent from Fig. 6 that the addition of the plates and thestrengthening members or bars does not require the removal of theoriginal I-bars 2|. Also, it will be understood that thevariousdiagonals may be connected with the plates according to any ofthe disclosures since it isnot necessary to connect any particulardiagonal in any particular way. That is, the end portions of thediagonals may overlap the plates as in Fig. 8 or they may abut theplates and be spliced to them as in Fig. 11.

Having thus set forth the nature of my invention, what I claim is:

1. The method of strengthening pin connected trusses while in positionin a fabricated structure, the same comprising providing a plate,forming a hole in said plate to receive a pin, splitting said plate intotwo sections by a cut passing through said hole, assembling the separateplate sections about the pin while it is in position in the structureand with the pin disposed through said hole, then welding the sectionsof the plate together along the line of said out, and then securing anend of a strengthening bar to the plate.

2. The method of strengthening pin connected trusses while in positionin a fabricated structure, the same comprising providing a plate,forming a hole in'said plate to receive a pin, splitting said plate intotwo sections by a cut passing through said hole, assembling the separateplate sections about the pin while it is in position in the structureand with the pin disposed through said hole, welding the sections of theplate together along the line of said cut, providing a block having anarcuate recess in one of its edges, securing said block to said platewith the edge of the recess in alignment with a portion of the edge ofthe hole in the plate whereby said block also engages the pin, and thensecuring an end of a strengthening bar to the plate.

3. The method of strengthening pin connected trusses while in positionin a fabricated structure, the same comprising providing a plate,forming a hole in said plate to receive a pin, splitting said plate intotwo sections by a cut passing through said hole, assembling the separateplate sections about the pin while it is in position in the structureand with the pin disposed through said hole and with the plate locatedapproximately in the center of the truss, welding the sections of theplate together along the line of said cut, disposing the sections of asplit pipe spacer about the pin at each side of the plate, securingtogether the sections of the respective spacers, and then anchoring oneend of a strengthening bar to the plate.

4. The method of strengthening pin connected trusses while in positionin a fabricated structure, the same comprising providing a plate,forming a hole in said plate to receive a pin, splitting said plate intotwo sections by a cut passing through said hole, assembling the separateplate sections about the pin while it is in position in the structureand with the pin disposed through said hole, welding the sections of theplate together along the line of said cut, arranging a strengthening barwith one of its end portions overlapping said plate, and then weldingsaid end portion to the plate.

5. The method of strengthening pin connected trusses while in positionin a fabricated structure, the same comprising providing a plate,forming a hole in said plate to receive a pin, splitting said plate intotwo sections by a cut passing through said hole, assembling the separateplate sections about the pin While it is in position in the structureand with the pin disposed through said hole, welding the sections of theplate together along the line of said cut, arranging a strengthening barwith one of its end portions abutting an edge of the plate, and thenwelding a splice plate to said end portion and to the plate.

6. In a method of strengthening pin connected trusses while they are inposition in the structure, the steps which comprise placing about thepin while it is in position in the structure a plate comprising twoseparate complementary sections having notches in adjacent edges adaptedto be placed in alignment to form an opening for the pin and with thepin in this opening, then 15 Welding the adjacent edges of the sectionstogether, and welding the end of a strengthening bar to the plate.

7. The method of strengthening pin connected trusses while they are inposition in the structure, comprising placing about each of two spacedpins while they are in position in the structure a plate comprising twoseparate complementary sections having notches in adjacent edges adaptedto be placed in alignment to form an opening for the pin and with thepins in these openings, then welding the two sections of the platetogether to form a unitary plate, and welding strengthening bars to therespective plates to connect them together.

ARTHUR G. LEAKE.

